Abstract: The present invention provides for an improved practical process for producing DDTr-free p,p'-dicofol and its formulations substantially free of the practically inactive o-p'-dicofol comprising either directly recrystallizing technical dicofol from a suitable solvent such as acetic acid or alkanes, or alternatively preparing the p,p'-dicofol by the steps of (a) dehydrohalogenating technical DDT to give DDE; (b) chlorinating DDE to give Cl-DDT; and (c) hydrolyzing Cl-DDT to dicofol, wherein the technical DDT is initially recrystallized from a suitable solvent such as lower alkyl alcohols and then recrystallizing the ressulting p,p'-dicofol from a suitable solvent such as acetic acid or alkanes.

Abstract: A one-step process for the preparation of nitrosamine-free dinitroaniline herbicides which involves contacting the crude dinitroaniline herbicide in the liquid state, after removal of excess amine, with an effective quantity of a hydrobromide salt of a p-amino benzoate ester, optionally in the presence of such an ester, passing a gaseous stream of air therethrough or applying a reduced pressure so as to essentially remove water present, resulting in an essentially nitrosamine-free product.

Abstract: A method for removal of nitrosoamine impurities from herbicides comprising contacting a nitrosoamine containing herbicide homogeneously with 0.001% to 1.0% of a compound having the formula: ##STR1## where X equals chlorine or bromine,R.sup.1 equals lower alkyl, anda equals zero or 1; provided that when a equals 1, then:R equals X.sub.n H.sub.(3-n) C(CH.sub.2).sub.p --, or ##STR2## or R.sup.2 COX, where R.sup.2 is selected from alkylene, alkenylene, alkynylene groups having 1 to 5 carbon atoms,n equals 1 to 3, andp equals zero, 1 or 2; and provided that when a equals zero, then:R equals aminophenyl,for a sufficient length of time to remove at least a substantial amount of the nitrosoamine.